High speed,reverse current driven interposer



United States Patent Primary Examiner-William S. Lawson Attorneys-Fred Jacob and W. Hugo Liepmann ABSTRACT: An actuator having a reverse current driven magnetic interposer for use in a high speed punch. The actuator comprises a permanent magnet, a pair of magnetic pole face elements joined by a magnetic shunt and having selectively energizable windings thereon, and a magnetic flexure spring having one end fixed to translate along a prescribed axis with respect to the pole face elements. The free end of the spring is held in a flexed no-punch position against the pole faces by permanent magnet force, released by a selectively applied electromagnetic force to spring into a punch position, and then returned to the no-punch position by a selectively applied electromagnetic force of reverse magnitude. 1n the punch position the spring is stiffened by a preform whereby a vertical punching force may be transmitted axially therethrough to a punch knife.

[72] Inventors Michael S. Shebanow;

Ronald E. Borelli, Medfield; Paul E. Nelson, l-lolliston, Mass. [21] Appl.No. 787,925 [22] Filed Dec.30,1968 [45] Patented Dec.15, 1970 [73] Assignee Honeywell Inc.

Minneapolis, Minn. a corporation of Delaware [54} HIGH SPEED, REVERSE CURRENT DRIVEN INTERPOSER 7 Claims, 6 Drawing Figs.

[52] U.S.C1 234/115 [51] lnt.Cl G06k 1/05 [50] FieldofSearch 234/115;

10l/93RC R [56] References Cited UNITED STATES PATENTS 3,049,990 8/1962 Brownetal 101/93 3,127,100 3/1964 Schmidt 234/115 :ezev. POWER SWITCH PKG. CIRCUIT all. ea

as 22 18 i PATENTEDUECISIQYO 35 471346 SHEET 1 BF 2 MICHAEL SSHEBANOW RONALD E BORELL/ PAUL E. NELSON l/ /\"I5N'I'( ms PATENTED DEC] 5 I970 SHEET 2 BF 2 3:28V POWER SWITCH MICHAEL s. SHEBANOW RONALD F. BORELLI WINDING 12.5 CURRENT Fig. 4 C.

+5. J DRIVER o INPUT I Fig. 4A.

POWER SWITCH 0 OUTPUT PAUL E. NELSON INVI-IN'H )RS BACKGROUND OF THE INVENTION The present invention concerns a new and improved actuator capable of operating for extended periods at high speed. In particular, the actuator includes an improved flexible magnetic interposer and driving means therefore wherein the interposer is positively controlled in both directions of movement for faster, more reliable operation.

For purposes of illustration the actuator is described in conjunction with a card punch unit wherein the invention has special application since its interposer acts as a magnetic armature, a return spring, and a column to transmit punching force. However, it will be understood that the novel actuator has utility in a number of other widely varied applications.

A universal requirement in the operation of a multihead high-speed punch unit is the rapid and synchronous operation of all punches which are simultaneously selected. Conventionally this is accomplished by applying reciprocating linear motion from a common motive source to a plurality of actuators, each adapted to transmit the motion to a corresponding punch knife. Each actuator includes an interposer which is selectively positioned in alignment with the. punch knife to transmit driving force thereto when punching is desired. The key to reliable operation then resides in the ability to shift the interposers rapidly and synchronously froma power transmitting position to an inactive position or vice versa.

Heretofore, available high-speed punch equipments have been relatively complex and expensive; generally including numerous moving pivots and wearing mechanisms which must be kept properly lubricated. The interposer was usually connected to a moving armature whereby the total mass to be moved was relatively large and the speed of operation therefore limited. Partially due to such complexity, the prior art equipments were subject to breakdowns during sustained periods of operation and were difficult to maintain in operating condition for appreciable periods of time. Frequently card punch equipments form part of a larger data processing system which is entirely disabled, atgreat hourly cost, when the aforesaid breakdowns occur.

U.S. Pat. No. 3,279,690 to Earl E. Masterson describes a more recently developed type of actuator, .including a magnetically controlled flat leaf spring wherein wear is minimized by the absence of pivot joints or other wearing .points requiring lubrication, which is easy to maintain in operating condition for extended periods. In the Masterson actuator the flat leaf spring of magnetic material is normally held in a flexed nonoperative position by the force of a permanent magnet. An electromagnetic force which opposes the permanent magnet force is selectively applied to free the spring whereby it springs into an operative or punch position so that a punching force may be applied axially therethrough to the punch knife. Upon completion of the punching operation, the electromagnetic force is terminated and the leaf spring is returned to the flexed position by the permanent magnet force.

The Masterson actuator is a significant improvement over the prior art in that it is extremely simple and reliable. However, the actuator has certain inherent characteristics which limit its use in an. ultra high speed punch operation. If a punching cycle is divided into four time increments, it is apparent that the spring of the Masterson actuator is held in a no-punch position during a first interval while the selection of the punches to be operated is accomplished. Following punch selection, the magnetic interposer is permitted to spring from a no-punch position to a punch position during a second interval. The punching operation is then carried out during a third interval; while the interposer is returned to the no-punch position during a fourth interval of the punching cycle. It should be apparentthat the provision of an improved mode of control over the moving interposer during the second and fourth intervals described above would result in a shorter punching cycle, thereby permitting higher speed operation.

Accordingly, it is a primary object of the present invention to provide an actuator having an improved interposer control which permits higher speed operation. It is another object of the present invention to provide a mechanical actuator of low mass for applying motion to a driven element which responds more rapidly to selectively applied control signals than other actuators of the prior art.

It is a further object of the invention to provide a simple and economical card punch unit utilizing magnetic flexure means wherein wear is minimized by the absence of pivots and other points requiring lubrication.

The foregoing objects are accomplished by a novel apparatus designed in accordance with the'present invention comprising an actuator having a reverse current driven magnetic interposer. The interposer comprises a metallic flexure spring normally held in a nonoperative position against a pair of pole faces magnetized by a permanent magnet. windings are provided adjacent to the pole faces and-a driving circuit is provided to selectively apply current to the windings in response to punch logic input signals. The electromagnetic forces generated by the energized windings act to positively control the movement of the flexure is both directions between the no-punch position and the punch position. Thus an electromagnetic force opposing the permanent magnet force is selectively applied in response to a punch signal to release the flexure whereby it springs into contact with a preform located adjacent a punch column. A synchronized punching force is then applied axially through the flexure to the punch knife. Upon completion of the punch stroke and return of the interposer to its upper position, the flexure is speedily returned to the flexed position by an electromagnetic force of aiding relationship to the force of permanent magnet. When theflexure is again in the no-punch position the aiding electromagnetic force is terminated and the flexure is retained solely by the permanent magnet.

BRIEF DESCRIPTION OF THE DRAWINGS Further object of the invention together with features and advantages thereof will become apparent from the following detailed description when read in conjunction with the accompanying drawings in which:

FIG. I is a perspective representation of an actuator having a magnetic interposer designed in accordance with the present invention;

FIG. 2 is a partial sectional view showing the details of a magnetic interposer as utilized in a high speed punch;

FIG. 3 is a schematic of a reverse current driver circuit for the interposer of the present invention; and

FIG. 4A-4C are diagrammatic representations of voltage and current wave forms relating to the circuit of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, the invention is explained with reference to a serial punch unit wherein the medium to be perforated, e.g. a card, moves in conventional manner below the lower end of a punch knife which has been omitted in the drawings for simplicity. While a single punch head has been shown in FIG. I for purposes of illustration, it should be understood that a serial punch unit would be comprised of a plurality of such units. For example, a multiple punch unit' with which the present invention could be utilized is described in U.S. PM. No. 3,411,709 to Masterson. Such a punch unit includes 24 individual punches disposed'in columns of 12 .punches each which are adapted to be simultaneously actuplication of punching force to the knife from a reciprocating column 9. The magnetic unit 3 includes a permanent magnet 11 of a suitable high retentivity material such as Alnico V and a pole face unit 12 including a shunt 14, upper pole face bar 15 and lower pole face bar 16. The upper bar, lower bar, and shunt are all formed of a suitable low retentivity magnetic material such as Cast Armaco and comprise a unitary structure. As shown, the shunt is provided with .openings 18, 19 therethrough by which the magnetic unit may be supported in a suitable frame not shown. The permanent magnet is fixed against the shunt, in alignment with the upper and lower bars and is retained in that position by its own force. An upper winding 21 is located on bar 15 and a lower winding 22 is provided on bar 16. As shown, these windings are electrically connected in series to terminals 24, 25 on the upper side of bar 15.

windings 21, 22 are adapted to be energized by a driving circuit which includes power switch 26, a switching amplifier 27 and a peaking circuit 28, in response to punch logic control signals applied to terminal 30 by a conventional punch selection unit, not shown. The circuit details and manner of operation of the driving circuit will be explained further in conjunction with FIGS. 3 and 4.

The interposer is shown fixed to and carried with. column 9 which reciprocates vertically as indicated by the arrow D under the influence of a conventional eccentric drive shaft and cam arrangement, not shown. The interposer includes an elongate flexure 32 of magnetic spring material mounted between a no-punch preform 33 and a punch preform 34. Flexure 32 and preform 34 are fixed adjacent each other and separated from column 9 by a spacer 36. Spacer 38separates flexure 32 from no-punch preform 33 by a predetermined air gap. Suitable fastening means 40 are provided to hold the magnetic spring, preforms and spacers in fixed alignment against the punch column. Preform 33 rests near the faces of bars 15, 16 and serves as a guide for flexure 32 in the nopunch position; while flexure 32 rests adjacent preform 34 in the punch position. Prefor'm 34 serves to stiffen the flexure whereby it serves as a column totransmit punching forces axially applied thereto. The preforms are fabricated of any suitable nonmagnetic material and are of predetermined thickness sufficient to provide the desired stiffness.

By referring to FIGS. 1 and 2 a better understanding of the movement of the interposer during a punching cycle can be gained. In the no-punch position flexure 32 is held adjacent preform 33 near the faces of upper bar and lower bar 16. When in this position flexure 32 is out of contact with the stationary punch knife 7 which travels-freely along slot 42 in column 9 as the latter reciprocates. Consequently, no force is applied to the punch knife when the flexure is in the no-punch position.

When a punch signal is received by the driving circuit of the actuator, an electromagnet force is applied in opposition to the permanent magnet force, sufficient to release the flexure 32 and permit it to spring into contact with preform 34 adjacent column 9. ln the latter position flexure 32 is vertically aligned with the top of punch knife 7, shown in FIG. 2 in its uppermost position. With flexure 32 aligned in the punch position an axial force is applied through the stiffened flexure to punch knife 7 as column 9 moves downward. This punching force is sufficient to drive the punch knife 7 down through a data processing card or document. As the .punch column travels upward stripper 43 engages step 46 of the punch knife and withdraws it to an upper position wherein it clears the freshly punched hole in the card. During this upper translation a reverse current is applied by the driver circuit 26, 28 to create in the actuator windings 21, 22 and electromagnetic force which aids the force of the permanent magnet, and is sufficient to withdraw flexure 32 into its no-punch position adjacent preform 33. Once flexure 32 is'in firm contact with preform 33, the electromagnetic force is terminated and flexure 32 is retained in position only by the force of the permanent magnet.

ln the punching application described herein the flexure 32 is mounted on column 9. However, it should be apparent that other arrangements are possible. Thus in certain applications the flexure 32 could be fixed to the frame of magnetic unit 3 to form a compact actuator of simple unitary. construction.

Referring now to FIGS. 3 and 4 a reverse current driving circuit particularly designed for use with the actuator of the present invention is shown. Punch logic signals are applied to terminal 30 which comprises the input of a two-stage switching amplified 50 including NPN transistors 65, 75. The switching amplifier is coupled to series windings 21, 22 of an actuator by a peaking circuit 28. The series windings are also connected to a two-level power switch 26 which produces positive and negative 28-volt outputs in accordance with a prescribed wave form. Y

The operation of the circuit of F IG. 3 will now be explained in detail in conjunction with the wave forms of FIG. 4. The driver input signal to terminal 30 is shown on line A of F IG. 4, while the output voltage waveform of switch 28 is shown on line B and waveform of the resulting current in windings 21, 22 is shown on line C. At time t the logic input voltage to terminal 30 changes from a plus 5 volts to zero. As the voltage at terminal 30 assumes a zero value, diode 52 is no longer back biased and provides a diversion path for current from the positive l5-volt source 98 through resistor 53 and terminal 56. This low impedance path diverts current which was previously flowing through diode 57, resistor 58 and resistor 59 to the negative l5-volt source 99 and the base 66 of transistor 65. Consequently, at time t the logic input voltage to terminal 30 changes from a plus 5 volts to zero. As the voltage at terminal 30 assumes a zero value, diode 52 is no longer back biased and provides a diversion path for current from the positive l5-volt source 98 through resistor 53 and terminal 56. This low impedance path diverts current which waspreviously flowing through diode 57, resistor 58 and resistor 59 to the negative l5-volt source 99 and the base 66 of transistor 65. Consequently, at time 5 the voltage of the base 66 of transistor 65 becomes more negative and the transistor turns off. The nonconduction of transistor 65 causes current to be diverted through resistor 67, diode 68 and resistor 69 to the negative l5-volt source 99 and to the base 76 of transistor 75. This in turn causes the base 76 of transistor 75'to become more positive whereby transistor 75 .turns on. The conduction of transistor 75 opens a circuit from power switch 26 through windings 21, 22, peaking circuit 28 and diode 79, on through transistor 75 to ground. Thus, windings 2 1, 22 are energized with a positive 28-volt power level from time t to time i As shown on line C, peaking circuit 28 comprising resistor 81 and capacitor 82 causes the current in the windings to reach a peak value b at 1 As capacitor 82 becomes fully charged the impedance of the peaking circuit increases and the winding current returns to a steady state a at t At time the logic input to terminal 30 returns to a positive 5-volt level, back biasing diode 52 and causing the voltage at the base 66 of transistor 65 to rise to a positive value, thereby permitting the transistor to conduct. The conduction of. transistor 65 recreates a low impedance path between the positive l5-volt source98 and ground, whereby the voltage at the base 76 of transistor 75 becomes more negative and transistor 75 turns off. The switching off of transistor 75 destroys the current path through windings 21, 22 and the winding current begins to decay from the value a towards zero as shown in the current waveform on line C.

Between when the winding current returns to zero and t the power switch output remains at a plus 28-volt level. However, at time t, the switch output changes to a negative 28-volt level and remains there until time During this period, the driver input level remains at plus 5 volts and consequently transistor 75 remains nonconductive. Thus, between and t a negative current path is completed from ground through bypass diode 84 and peaking circuit 28 on through windings 21, 22 to the power switch 26. The peaking circuit again causes a steep buildup of current in the windings to level d at time t as shown in FIG. 4. However, the power switch output returns to a positive 28-volt-level at before the capacitor 82 is fully charged.

Consequently, the current level begins to decay toward zero between times :6 and I Between 2 and 1 both the driver input level and the power switch output remain at positive voltage levels whereby no conduction occurs through windings 21, 22.

From the foregoing, the manner in which the winding current shown in F IG. 4 is correlated to the movement of the flexure 32 should be apparent. Thus, between it, and t the winding current generates an electromagnetic flux in the magnetic circuit of the actuator which opposes the flux from permanent magnet 11. This flux, generated in bars l5, 16 of the magnetic circuit, is of sufficient magnitude to cause nearly all thepermanent magnet flux to be diverted through the shunt 14 whereby flexure 32 is released to spring into contact with punch preform 34.

The synchronized punching force is then applied from the punch column 9 to the flexure to drive the punch knife downward.

Between and t the electromagnetic fluxdecays in accordance with the decrease in the winding current and the permanent magnet flux again dominates the magnetic circuit of the actuator. However, the punched magnet force is insufficient to influence the movement of flexure 32 during the final portion of the punch step which transpires between 1,, and t Between 1, and t an electromagnetic force is developed which aids the permanent magnet force and begins to draw the interposer 32 back to a no-punch position shortly after the knife 7 clears the punched hole in the card. This aiding flux reaches its peak value at i at which time flexure 32 reaches its rest position adjacent the preform 33. 5. 32 reaches the nopunch position the electromagnetic force is terminated and the flexure is retained solely by the permanent magnet force. As shown, the aiding electromagnetic fluxdecays to 0 at t The interval between I, and 1,, is provided for the logical selection of the punches to be actuated on the next cycle of operation.

It should be apparent that the movement that which the flexure mustexecute to be in or out of alignment with its corresponding punch knife is relatively small. Furthermore, this movement is positively controlled in both directions by electromagnetic forces generated by the winding currents. Accordingly, a punch unit which employs an actuator of the type disclosed herein is capable of operating at ultra high speeds. Such high speed operation is accomplished by the present system, which is of relatively simple and inexpensive construction. Since the contacting component parts all reciprocate together the wear of these parts is minimized and lubrication of the actuator is not required. Consequently, fewer breakdowns are experienced under sustained periods of operation and longer time intervals are permitted between scheduled maintenance.

It should be clear that the invention is not'limited to the use of a serial punch unit having any fixed number of heads. Rather, the invention may be used with a single punch, if desired, or with single or double column arrangements of punches. Further more, the invention may be used in any other application where a driver element is to be selectively positioned to transmit motion to a driven element.

lclaim:

l. A mechanical actuator comprising:

first and second spaced guide surfaces;

' an elongated flexure positioned therebetween and normally in flexibly conforming contact with said first guide surface;

first electromagnetic means for selectively actuating said flexure to assume a position in flexibly conforming contact with said second guide surface;

means for reciprocating said flexure in a lengthwise direction; 1

a driven element positioned to have motion imparted thereto by said flexure when the later approaches one extreme of said reciprocation while in contact with one of said guide surfaces;

second electromagnetic means for selectively actuating said flexure to reassume a position in flexibly conforming contact with said first guide surface; and

means for retaining said flexure in contact with said first guide surface with said first and second electromagnetic means inactive.

2. An actuator as described in claim 1 wherein said means to normally retain said flexure in contact with said first guide surface comprises permanent magnet means.

3. In anactuating arrangement including reciprocating driving means arranged to be reciprocatingly thrust along a prescribed drive path, the combination therewith comprising:

elongated flexure means for selectively transmitting said thrust from said driving means to said driven means at a driving position thereof, said flexure means having an elongated axis relatively along said drive path and having a prescribed asymmetric cross-sectional stiffness, being relatively stiff along a first cross-sectional dimension and relatively resilient along a second cross-sectional dimension orthogonal to said first dimension;

first electromagnetic means to selectively position said flexure means in a nondriving position by thrusting it along said second resilient dimension thereof relatively transverse said drive path for prescribed periods; cross-sectional second electromagnetic means to selectively actuate said flexure means to assume said driving position along said path; and

means for retaining said flexure in a nondriving position until said flexure is so selectively actuated.

4. An actuating arrangement as described in claim 3 wherein said means to normally retain said flexure in a nondriving position until selectively actuated comprises permanent magnet means.

5. In an actuator:

first and second spaced guide surfaces;

an elongated flexure positioned therebetween;

permanent magnet means to retain said flexure in flexibly conforming contact with said first guide surface, said permanent magnet means having electrical windings thereon;

means for reciprocating said flexure in a lengthwise direction;

a driven element positioned to have motion imparted thereto by said flexure when the latter approaches one extreme of said reciprocation while in contact with one of said guide surfaces; 7

first circuit means for selectively applying electrical current to said windings to actuate said flexure to assume a position in flexibly conforming contact with said second guide means; and

second circuit means for selectively applying reverse current to said windings to actuate said flexure to reassume the position in flexibly conforming contact with said first guide surface.

6. An actuator as described in claim 5, further including peaking circuit means for generating current maxima in said windings at predetermined times.

7. An actuator as described in claim 6, wherein said windings are connected in electrical series.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,547,346 Dated Dec. 15, 1970 Patent No.

Inventor-(s) Michael S, Shebanow et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6 lines 31 and 32 cancel c'ross -sectional" Signed and sealed this 11th day of April 1972 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GO'I'TSCHALK Attesting Officer Commissioner of Paten l hull 

